Bokeh

To quote the Nikon USA site: Bokeh is defined as “the effect of a soft out-of-focus background that you get when shooting a subject, using a fast lens, at the widest aperture, such as f/2.8 or wider.” Simply put, bokeh is the pleasing or aesthetic quality of out-of-focus blur in a photograph.

Good Bokeh can really help the subject pop out against the background with a nice contrasting or complimentary colour. I use a 5.6 lens and still can achieve some interesting bokeh.